Liquid concentrate for the preservation of cosmetic and pharmaceutical products

ABSTRACT

The invention relates to a liquid concentrate for the preservation of cosmetic an pharmaceutical prod nets which comprises 3-iodo-2-propynyl butylcarbamate (IPBC), at least on liquid carrier selected from the group consisting of: polyvalent alcohols, glycol esters and glycol ethers, and at least one stabilizer selected from the group consisting of: formic acid, formic acid salts, and format esters, and comprising no additional carboxylic acid selected from the group consisting of: benzoic acid, propionic acid, salicylic acid, sorbic acid, 4-hydroxybenzoic acid, dehydroacetic acid and 10-undecylenic acid and a salt thereof being present.

The invention relates to a liquid concentrate based on 3-iodo-2-propynylbutylcarbamate (IPBC) and to its use in the preparation and preservationof cosmetic and pharmaceutical products.

Preservatives are used in many products or systems with an aqueous phasein order to avoid harmful and spoiling effects, in particular microbialeffects, on the product. Important fields of use of preservatives arecosmetic products, such as shampoos, shower gels and bath gels, but alsohigh-value care cosmetics, such as creams, emulsions, lotions and gels.Preservatives are also used in cleaning, care and hygiene products forthe home (e.g. antimicrobial hand cleansers) and body care (e.g.toothpaste).

IPBC has of late played an ever greater role in the preservation of suchproducts. It is available as a white powder and has the disadvantagethat it is only very sparingly soluble in water (approximately 0.1 g/lat 20° C.). In the solid form, it has performance disadvantages withregard to handling and metering. For this reason, industry prefers tofall back on liquid products and is interested in a liquid IPBC form.

In addition, the colour of the products is assuming an ever greaterrole. Colourless or pastel-coloured products, which furthermore shouldhave a high colour stability, are increasingly desired.

For example, EP 0 757 518 is known, in accordance with whichcombinations of IPBC with formaldehyde-depositing compounds are used. Afurther example of known IPBC formulations is EP 0 484 172, in whichcombinations of IPBC with 1,3,5-tris(hydroxyethyl)hexahydrotriazine aredescribed. DE 100 34 138, which describes combinations of IPBC withphenoxyethanol, is also known.

IPBC is actually sufficiently soluble in most organic solvents andcompatible with many active agents, additives and auxiliaries used incosmetics, yet the colour stability of liquid concentrates still causesgreat problems, which can be put down to their low solubility in waterand their active groups in the IPBC molecule. Sensitivity to light, heatand oxidation are to be added, resulting in the formation of coloureddecomposition products. Odour development is also frequently inadequate.

It is therefore an object of the present invention to make available aliquid product in the form of a liquid concentrate for the preservationof cosmetic and pharmaceutical products based on IPBC which iscolour-stable, which, in addition to the pronounced fungicidal action,also shows a very good bactericidal action, which also is stable withreference to the active agent content and which has good organolepticproperties.

A liquid concentrate for the preservation of cosmetic and pharmaceuticalproducts based on 3-iodo-2-propynyl butylcarbamate (IPBC) is proposed toachieve this object, which liquid concentrate is characterized in thatit, in addition to IPBC, comprises a liquid carrier chosen frompolyvalent alcohols, glycol esters and glycol ethers or any mixturethereof and a stabilizer chosen from formic acid, formate salts andformate esters or any mixture thereof, no additional carboxylic acidchosen from benzoic acid, propionic acid, salicylic acid, sorbic acid,4-hydroxybenzoic acid, dehydroacetic acid and 10-undecylenic acid or asalt thereof being present.

The proportions of the individual components in the liquid concentrategiven below in weight % refer to the weight of the combined concentrate,unless otherwise specified.

It has surprisingly been shown that, through the combination of IPBCwith a liquid carrier and one of the formic acid derivatives mentionedas stabilizer, a product is obtained which has a stable colour, a stableactive agent and an acceptable odour, without the microbiologicalactivity being reduced.

In this connection, “colour-stabilizing action” means that theconcentrate, optionally diluted with solvent or in the product to bepreserved, is subject to no obvious colour change (e.g. turning brown)under conventional storage conditions. Such a colour change can, forexample, be monitored with known test methods (e.g. determination of theHazen colour number or Gardner colour number).

The term “active agent stability” means that, under conventional storageconditions over a period of at least 4 weeks, preferably 3 months, noprecipitate perceptible by the senses or no cloudiness appears in theconcentrate. “Conventional storage conditions” is to be understood, forexample, as storage at ambient temperatures from 15 to 25° C. in dry,ventilated spaces. However, the liquid concentrate according to theinvention also exhibits an improved storage stability over the periodmentioned at temperatures which are clearly higher than conventionalstorage temperatures, preferably higher than 40° C. (e.g. 50° C.), whichis particularly advantageous for use thereof in tropical regions.

The invention also relates to a process for the preparation of such aliquid concentrate and to the use of the liquid concentrate according tothe invention in the preparation and/or preservation of cosmetic andpharmaceutical products.

The liquid concentrate according to the invention comprises IPBC, withreference to the total weight, in an amount of 0.01 up to 20 weight % ofIPBC, preferably 0.1 up to 5 weight % of IPBC, especially 0.1 up to 2weight % of IPBC and particularly preferably up to 1 weight % of IPBC.

The liquid concentrate comprises, as liquid carrier, a polyvalentalcohol, in particular a diol, preferably a glycol and more preferablyethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol,1,2-butylene glycol, 1,3-butylene glycol, 1,4-butylene glycol,1,2-pentanediol, 1,3-pentanediol, 1,4-pentane-diol or 1,5-pentanediol,or a glycol ester or glycol ether, in particular an ethylene glycol,propylene glycol or butylene glycol, preferably diethylene glycol,triethylene glycol or a polyethylene glycol, or any mixture thereof.Triethylene glycol or 1,2-propylene glycol are particularly preferred.

The amount of liquid carrier present in the liquid concentrate accordingto the invention ranges, with reference to the total weight, from 30 to99.989 weight %; it preferably amounts to at least 50 weight % andespecially at least 95 weight %.

The stabilizer component of the liquid concentrate is chosen from formicacid, sodium formate, potassium formate, formic acid propylene glycolmono- or diester or formate esters formed in situ or any mixturethereof, in particular formic acid. 85% or 98-100% formic acid can, forexample, be used.

The stabilizer component, is present therein in an amount of 0.001 to 20weights, preferably 0.05 to 10weight %, more preferably still 0.05 to 5or to 2 weight % and for example less than 2 or less than 0.5 weight %or even less than 0.2 weight %.

The liquid concentrate can comprise additional active agents, functionaladditives and/or auxiliaries.

Polybiguanide (frequently also described as polyhexamethylenebiguanidehydrochloride) and/or a polybiguanide salt is possible as additionalactive agent, preferably in an amount, with reference to the totalweight, of 0.1 up to 20 weight %, more preferably up to 5 weight %,particularly preferably up to 2 weight % and most preferably up to 1weight %. For example, a 20% polyhexamethylenebiguanide hydrochloride inanhydrous or virtually anhydrous grade can be used.

The weight ratio of IPBC to polybiguanide or polybiguanide salt is in apreferred embodiment 100:1 to 1:100, preferably 10:1 to 1:10 and morepreferably 1:2 to 2:1.

In an additionally preferred embodiment, the concentrate comprises ≦1weight % of IPBC, in particular 1 weight %, and ≦1 weight % ofpolybiguanide/polybiguanide salt, in particular 0.95 weight %.

Depending on the field of application, it may be advantageous if theliquid concentrate is either anhydrous or comprises water as auxiliary,the content of water then preferably amounting to, based on the totalweight, 0.01 up to 10 weight %, more preferably up to 5 weight %, morepreferably still up to 4.5 or up to 4 weight %, particularly preferablyup to 0.2 weight % (virtually anhydrous). The liquid concentrates arepreferably anhydrous or virtually anhydrous.

The liquid concentrate can comprise, as additional active agent, inaddition to or in place of the polybiguanide compound, a paraben, inparticular methyl-, ethyl-, propyl- or butylparaben, a quaternaryammonium compound, in particular polyhexamethylene-biguanide or a saltthereof, a benzalkonium salt, in particular benzalkonium chloride,formaldehyde or a formaldehyde-depositing compound or a salt thereof, inparticular dimethyloldimethylhydantoin (DMDMH), imidazolidinylurea,diazolidinylurea, hexetidine, 5-bromo-5-nitro-1,3-dioxane (bronidox),2-bromo-2-nitro-1,3-propanediol (bronopol), 1,3,5,7-tetraazaadamantane(hexamethylenetetramine), 4,4-dimethyl1,3-oxazolidine, benzyl alcoholhemiformal, 5-ethyl-1-aza-3,7-dioxabicyclo[3.3.0]octane,1-(3-chloroallyl)-3,5,7-triaza-1-azoniaadamantane chloride or mixturesthereof, phenoxyethanol, phenoxypropanol, benzyl alcohol, a halogencompound, in particular dibromodicyanobutane (DBDCB), an amidinecompound, in particular hexamidine or dibromohexamidine, or a saltthereof, or an isothiazolone, in particular N-methylisothiazolone orN-octylisothiazolone, or any mixture of the abovementioned compounds.

Preferred antimicrobial active agents which can be used to improve theeffectiveness and/or to broaden the spectrum of activity areo-phenylphenol and its salts, zinc pyrithione, inorganic sulphites andbisulphites, sodium iodate, dibromohexamidine and its salts,triclocarban, 4-chloro-m-cresol, triclosan, 4-chloro-3,5-dimethylphenol,2-hydroxy-4,4′-dichlorophenyl ether (e.g. Tinosan HP 100),polyhexamethylenediguanide and its salts,1-(4-chlorophenoxy)-1-(imidazol-1-yl)-3,3-dimethyl-2-butanone,1-hydroxy-4-methyl-6-(2,4,4-trimethylpentyl) -2-pyridone and itsmonoethanolamine salt, 1,2-dibromo-2,4-dicyanobutane, bromochlorophen,5-chloro-2-methyl-3(2H)-isothiazolone, 2-methyl-3(2H)-isothiazolone,2-benzyl-4-chlorophenol, 2-chloroacetamide, chlorohexidine and itssalts, N-[(C₁₂-C₂₂)alkyltrimethyl]ammonium salts, hexamidine and itssalts, glutaraldehyde, silver chloride, benzethonium chloride,benzalkonium salts (e.g. benzalkonium chloride), or mixtures of theabovementioned compounds.

In addition, a large number of substances or combinations of substancescan be used as additional functional additives, auxiliaries or activeagents (cosmetic additives) for the basic formulation (in place of theacids mentioned below, the corresponding salts are optionally used). Theadditives can be anion-active or cation-active. Examples of additivesare skin care substances and moisture-retaining factors (e.g. urea orSensiva SC 50), complexing agents (e.g. EDTA), essential oils andnatural extracts, amphoteric surfactants, surfactants, cleaningadditives and disinfection active agents (e.g. cocoamidopropyl betaine),fragrances, antiacne or antidandruff active agents (e.g. octopirox andLipacid C8G), fungicides, dyes, corrosion inhibitors, disinfectionactive agents and antiseptics (e.g. octenidine dihydrochloride), bitterprincipals (e.g. denatonium salts), screening agents (e.g.2-phenylbenzimidazolesulphonic acid), deodorant active agents (e.g. zincphenolsulphonate or Sensiva SC 50), oral care active agents (e.g.potassium monofluorophosphate), isothiazolones, carbohydrate compounds(e.g. alkylpolyglycosides, starch or cellulose derivatives andcyclodextrins), alkali metal chlorides (e.g. NaCl or KCl), anionicsurfactants (e.g. lauryl ether sulphates), plant extracts and oils.Quaternary ammonium salts (e.g. cetyltrimethylammonium chloride orbromide, cetylpyridinium chloride or didecyldimethylammonium chloride)can be used as possible cation-active active agents.

Many of these cosmetic additives also have a multifunctional action. Insome cases, synergistic increases in activity of the liquid concentratesaccording to the invention with the additives may also arise.

Additional additives, auxiliaries and/or active agents are, for example,thickeners, buffers, antifoaming agents, solubility promoters,antistatic agents, polymers and/or antioxidants.

In individual cases, the type and amount of additional active agents canbe established by a person skilled in the art in a simple and rapidmanner by a few experiments, it being possible for the active agentsystem obtained, which includes the liquid concentrate according to theinvention, to have a broad or also very specific application potential.

The preparation of the concentrates is carried out by simple mixing. Forexample, the solid components are dissolved with stirring in the liquidcomponents and the additional additives and auxiliaries are stirred inhomogeneously. The mixture is optionally heated (e.g. up to 50° C.

With regard to the preparation process, in which the constituents aremixed with one another in any sequence, it is optionally advantageousfor the liquid concentrate to be stirred or allowed to stand at anincreased temperature for a period of time. This temperature treatmentresults in a surprisingly increased stability. In the course of this,the mixture is advantageously, subsequent to the mixing together, heldfor 0.5 to 48 hours at a temperature of 30 to 70° C., optionally withstirring, in particular 30 up to 60° C., more preferably at 30 up to 50°C. For example, a temperature treatment over 6 h at 50° C., 24 h at 40°C. or 48 h at 30° C. is possible. The higher the temperature, theshorter the period of time of the temperature treatment can be.

It is advantageous that the liquid concentrates according to theinvention can be incorporated in the cosmetic and pharmaceuticalproducts by simple dilution. This offers handling and cost advantagescompared with the use of individual substances, which are often powdersor granules and have to be dissolved or dispersed before incorporationin the product to be preserved. Storage and transportation costs canalso be reduced by the concentrate form.

A further advantage is that the liquid concentrates according to theinvention are suitable as solubility promoters for cosmetic additiveswith little or limited solubility in water or as solvents or carriersfor various cosmetic additives.

The liquid concentrate according to the invention preferably exists as aclear homogeneous solution. However, should precipitates possibly ariseat a low pH in the concentrate or in predilutions, these can bereversibly dissolved by simple dilution or by correcting the pH.However, it is also possible to prepare the liquid concentrate as ahomogeneous-disperse preparation, it being preferable in such cases toavoid relatively large amounts of crystallized active agents in thepreparation. In addition, the liquid concentrate can exist in the formof a paste.

In a preferred embodiment, an “aged” mixture of glycols and/or glycolethers and formic acid is used as carrier/stabilizer combination. Theexpression “aged” means in this connection that combinations of glycolsand/or glycol ethers and. formic acid are held at an increasedtemperature (up to boiling point of the mixture) for a sufficiently longperiod of time, optionally with stirring, until the smell of formic acidhas largely or completely disappeared. Ester formation between theformic acid and the glycol and/or glycol ether possibly occurs duringthis ageing, the exact structure of the compounds formed being unknown.Alternatively, glycol (ether) formates can also be dissolved in glycoland/or glycol ether and the combination can be used together with theIPBC.

Liquid concentrates which smell very little or not at all of formic acidare particularly preferred.

The pH of the liquid concentrate is 1 to 10, preferably 3 to 7 andpreferably 5 to 7 (measured after preparation of a fresh solution oremulsion with water). For example, the pH of a 2 weight %solution/emulsion in water ranges from 2.5 to 5.5 or approximately 3.

The liquid concentrates according to the invention therefore have, inparticular, the following advantages:

-   liquid;-   concentrate form;-   handling and cost advantages;-   homogeneous;-   limpid;-   low viscosity;-   colourless to faintly coloured;-   odourless or virtually odourless;-   very good thermal stability;-   very good colour stability;-   very good active agent stability;-   broad spectrum of activity with improved (synergistic) effectiveness    compared with known IPBC products;-   can, during the production of cosmetics, serve as solvent,    solubility promoter or carrier for other ingredients (e.g.    fragrance, or the like);-   safe—no residue risk upon use;-   stable at low temperatures, liquid and pumpable at low temperatures    (even after 12 months at, e.g., −5° C.); and-   miscible, compatible with a wide range of ingredients.

The liquid concentrates according to the invention are suitable for thepreparation of cosmetic products, in particular for leave-on products,such as creams, lotions, gels or moist wipes, the pH values of whichgenerally range from 5 to 8, or for rinse-off products, such asshampoos, the pH values of which are generally less than 7, inparticular less than 6.

Furthermore, the liquid concentrates according to the invention aresuitable as additive for pharmaceutical products and for washing,cleaning, care, body care and hygiene products. In addition to thepreservation, the concentrates according to the invention contribute tothe antimicrobial effectiveness.

The invention is illustrated below by means of examples.

EXAMPLES

In the examples and comparative examples, polybiguanide was used as a 20weight % product in water; i.e. 4.75 weight % of 20% polybiguanidecorresponds to 0.95 weight % of active agent.

The following formulations were prepared by introducing the liquidcarrier, adding the IPBC and the polybiguanide and then stirring until aclear solution was formed. The stabilizer was then added andhomogeneously distributed with stirring. Clear solutions were obtainedby doing this.

Example 1

1.00 weight % IPBC 4.75 weight % 20% Polybiguanide 2.50 weight % 98-100%Formic acid 91.75 weight %  Triethylene glycol

Example 2

1.00 weight % IPBC 4.75 weight % 20% Polybiguanide 0.50 weight % 97%Sodium formate 93.75 weight %  1,3-Butanediol

Example 3

1.00 weight % IPBC 4.75 weight % 20% Polybiguanide 2.90 weight % Formicacid (85% in water) 91.35 weight %  1,2-Propylene glycol

Example 4

0.95 weight % IPBC 4.75 weight % 20% Polybiguanide 2.20 weight % Formicacid (85% in water) 92.10 weight %  1,2-Propylene glycol

COMPARATIVE EXAMPLES Comparative Example 1

1.00 weight % IPBC 4.75 weight % 20% Polybiguanide 94.25 weight % 1,2-Propylene glycol

Comparative Example 2

1.00 weight % IPBC 4.75 weight % 20% Polybiguanide 94.25 weight % Triethylene glycol

Comparative Example 3

1.00 weight % IPBC 4.75 weight % 20% Polybiguanide  1.0 weight %Glycolic acid 93.25 weight %  Triethylene glycol

Comparative Example 4

1.00 weight % IPBC 4.75 weight % 20% Polybiguanide  1.0 weight % Lacticacid (80-90%) 93.25 weight %  Triethylene glycol

Comparative Example 5

1.00 weight % IPBC 4.75 weight % 20% Polybiguanide  1.0 weight % Benzoicacid (>99.5%) 93.25 weight %  Triethylene glycol

Comparative Example 6

1.00 weight % IPBC 4.75 weight % 20% Polybiguanide  1.0 weight % Formicacid (98-100%) 93.25 weight %  Phenoxyethanol

The examples according to the invention all showed good stability withregard to odour, colour and active agent, while the products of thecomparative examples did not display sufficient stability with regard toodour, colour and active agent.

The results of these investigations are collated in Tables 1 and 2.

TABLE 1 Storage stability, low-temperature stability and colourstability of the liquid conc ntrates Example 1 Example 3 Example 4Comparative Example 1 Appearance immediately clear liquid/ clear liquid/clear liquid/ clear liquid/almost after preparation colourlesscolourless colourless colourless Zero values Odour pungent pungentpungent almost neutral Colour number/Hazen 14 6 6 27 IPBC (%) 1.00 0.960.92 0.98 Polybiguanide (%) 0.97 0.94 0.98 0.98 3 Months storage in bluepolyethylene bottles Appearance All samples through all followingstorage conditions o.V. (clear liquids) −5° C. Odour not pungent notpungent not pungent almost neutral Colour number/Hazen 99 6 7 74 IPBC(%) 0.98 1.00 0.94 0.98 Polybiguanide 1.00 0.94 0.93 1.01  4° C. Odournot pungent not pungent not pungent almost neutral Colour number/Hazen64 97 8 553 IPBC (%) 0.98 0.99 0.93 0.98 Polybiguanide 1.01 0.95 0.941.01 25° C. Odour not pungent not pungent not pungent almost neutralColour number/Hazen 33 16 16 346 IPBC (%) 0.97 0.97 0.89 0.88Polybiguanide 1.02 0.96 0.96 1.02 ATL (ambient Odour not pungent notpungent not pungent almost neutral temperature/light) Colournumber/Hazen 30 9 10 422 IPBC (%) 0.97 0.97 0.95 0.87 Polybiguanide 1.010.96 0.95 1.01 Window/South Odour not pungent not pungent not pungentalmost neutral Colour number/Hazen 78 22 21 773 IPBC (%) 0.94 0.96 0.950.77 Polybiguanide 1.02 0.97 0.97 1.02 40° C. Odour not pungent notpungent not pungent almost neutral Colour number/Hazen 189 568 495 560IPBC (%) 0.88 0.65 0.66 0.58 Polybiguanide 1.04 1.01 1.00 1.03

TABLE 2 Storage stability, low-temperature stability and colourstability of liquid concentrates according to the invention ComparativeComparative Comparative Comparative Example 3 Example 4 Example 5Example 6 Example 2 Appearance immediately clear, colourless clear,colourless clear, colourless clear, colourless clear, colourless afterpreparation Hazen colour number 7 9 9 5 5 Odour characteristiccharacteristic characteristic pungent not pungent IPBC content 0.98 1.011.03 1.01 1.00 After storage for 4 weeks at ambient temperature/light ina glass jar: Appearance clear clear clear clear clear Hazen colournumber >1 000 >1 000 >1 000 >1 000 5 Gardner colour number 6.4 6.4 5.8 00 Odour o.V. o.V. o.V. not pungent o.V. After storage for 4 weeks at+50° C. in a glass jar: Appearance clear clear clear clear clear Hazencolour number >1 000 >1 000 >1 000 >1 000 122 Gardner colour number 5.45.4 5.5 6.6 0.4 Odour o.V. o.V. o.V. not pungent o.V. IPBC content 0.76%0.74% 0.72% 0.45% 0.96% IPBC loss in % 22% 27% 30% 55% 4%

It follows from Tables 1 and 2 that the liquid concentrate according tothe invention show a clearly improved stability.

For the colour stability investigations, the liquid concentrates werestored in clear glass and the Hazen or Gardner colour number (see testmethods) was determined immediately after preparation on a freshlyproduced preparation, and also after the period of time given andstorage at the temperatures given,

Test Methods:

The Hazen colour number (DIN-ISO 6271, also known as “APHA method” or“platinum/cobalt scale”) is defined as mg of platinum per 1 litre ofsolution. For the Hazen stock solution, 1.246 g of potassiumhexachloroplatinate(IV) and 1.00 g of cobalt(II) chloride are dissolvedin 100 ml of hydrochloric acid and made up to 1,000 ml with distilledwater, The Hazen colour scale is used for assessing the colour ofproducts which are almost limpid. It is graduated more closely in thelight-yellowish region than the iodine colour scale and extends as faras limpid shades of colour.

The Gardner colour number is defined in DIN-ISO 4630. The light-yellowGardner colour numbers (1 to 8) are based on potassium chloroplatinatesolutions and the colour numbers 9 to 18 on iron(III) chloride,cobalt(II) chloride and hydrochloric acid solutions.

The respective concentrate was introduced into a cell and then thecolour number was measured using a colorimeter of Lico® 2 00 type (DrLange GmbH, Berlin).

The odour development was examined organoleptically. The odours were ineach case assessed by 3 people.

1. A method for preserving cosmetic and pharmaceutical productscomprising the steps of: providing a liquid concentrate preservativecomprising: a) 3-iodo-2-propynyl butylcarbamate (IPBC). b) at least oneliquid carrier, c) at least one stabilizer, and d) polyhexamethylenebiguanide, or a salt thereof; and mixing said concentrate in a cosmeticor pharmaceutical product by simple dilution, wherein, the weight ratioof said IPBC to said polyhexamethylene biguanide is from about 100:1 toabout 1:100, and no additional carboxylic acid chosen from benzoic acid,propionic acid, salicylic acid, sorbic acid, 4-hydroxybenzoic acid,dehydroacetic acid, and 10-undecylenic acid, or the salts thereof, ispresent in said concentrate.
 2. The method according to claim 1, whereinsaid IPBC is from about 0.01% to about 20% by weight of saidconcentrate.
 3. The method according to claim 1, wherein said liquidcarrier comprises at least one component selected from the groupconsisting of polyvalent alcohols, glycol esters, and glycol ethers. 4.The method according to claim 3, wherein said polyvalent alcohol is atleast one component selected from the group consisting of diol, glycol,ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol,1,2-butylene glycol, 1,3-butylene glycol, 1,4-butylene glycol,1,2-pentanediol, 1,3-pentanediol. 1,4-pentanediol, 1,5-pentanediol,glycol ester, glycol ether, ethylene glycol, propylene glycol, butyleneglycol, diethylene glycol, triethylene glycol, polyethylene glycol,triethylene glycol, and 1,2-propylene glycol.
 5. The method according toclaim 1, wherein said stabilizer comprises at least one componentselected from the group consisting of formic acid, formate salts,formate esters, sodium formate, potassium formate, and formic acidpropylene glycol monoester, diester, and formate esters formed in situ.6. The method according to claim 5, wherein said stabilizer consists offormic acid.
 7. The method according to claim 1, wherein said stabilizeris from about 0.001% to about 20% by weight of said concentrate.
 8. Themethod according to claim 1, wherein said concentrate further comprisesa component selected from the group consisting of at least onefunctional additive, at least one auxiliary, and mixtures thereof. 9.The method according to claim 1, wherein said polyhexamethylenebiguanide is up to about 20% by weight of said concentrate.
 10. Themethod according to claim 1, wherein said weight ratio ranges from about10:1 to about 1:10.
 11. The method according to claim 1, wherein saidIPBC is less than about 1% by weight of said concentrate, and saidpolyhexamethylene biguanide is less than about 1% by weight of saidconcentrate.
 12. The method according to claim 1, wherein, saidconcentrate further comprises at least one functional additive, and saidconcentrate is absent an auxiliary.
 13. The method according to claim 8,wherein said auxiliary comprises water.
 14. The method according toclaim 13, wherein said water is from about 0.01% to about 10% by weightof the concentrate.
 15. The method according to claim 8, wherein saidconcentrate further comprises a paraben.
 16. The method according toclaim 8, wherein said concentrate further comprises a quaternaryammonium compound.
 17. The method according to claim 8, wherein saidconcentrate further comprises a halogen compound.
 18. The methodaccording to claim 8, wherein said concentrate further comprises anamidine compound.
 19. The method according to claim 8, wherein saidconcentrate further comprises isothiazolone.
 20. The method according toclaim 8, wherein said concentrate further comprises benzalkonium salt.21. The method according to claim 8, wherein said concentrate furthercomprises formaldehyde or a formaldehyde-depositing compound or a saltthereof.
 22. The method according to claim 8, wherein said concentratefurther comprises at least one of phenoxyethanol, phenoxypropanol, andbenzyl alcohol.